DESCRIPTION: Swallowing requires coordination of more than 20 muscles. However the activity pattern of these muscles during the oral and pharyngeal stages of the swallow is poorly understood and little is known how feedback from the periphery is integrated with control from higher centers to produce a swallow. Furthermore, the nature of the swallow changes at weaning, but almost no information exits on developmental differences in motor patterns. Such detailed information is essential not only for the understanding of a normal swallow, but also for the clinical management of dysphagia. This project will develop a complete model of swallowing function in the pig at three ages: neonate, near weaning infant and postweaning. At each age, in two separate set of experiments, the movements of the bolus and of the oropharyngeal structures used in swallowing will be determined cineradiographically, with synchronous electromyographic recordings of the muscles involved. The first set of experiments will use awake normally feeding animals and record from the limited number of muscles accessible without extensive surgery. The second set will be a two-stage terminal experiment. In the first stage under maintained Ketamine anesthesia, activity will be recorded from the larger number of muscles reached by more extensive surgery; swallows will be elicited in the Ketamine anesthetized animals by stimuli similar to those of normal feeding. In the second stage, the motor cortices or cerebral hemispheres will be removed and swallows elicited by the same stimuli as in the first stage. This will test whether the pattern of muscle activity during the swallow is controlled by a fixed brainstem motor pattern that changes with age or whether this motor pattern can be modified by the nature of the stimuli initiating the swallow. Taken together these experiments will determine the effects of age and outside influences on the nature of swallow.